As a result of rapid advances in design and manufacturing technology, liquid crystal displays (LCD) have recently become available which have a display quality that can match that of cathode ray tubes. However, to achieve the higher resolution for LCDs, it is necessary to drive the LCDs at accelerated speeds. Consequently, various attempts have been made for designing circuitry for driving LCDs at accelerated speeds.
In such LCDs, a signal, such as an analog or digital video signal, is used to control a pixel. This signal is applied on a number of columns by buses or "display lines" and is selectively gated at the appropriate time to each pixel of the display by gate signals applied to rows or gate supply buses.
Such displays typically employ one line driver per display line, sometimes referred to as "data driver". The data drivers are typically arrayed along an edge of the display substrate along a distance of several inches. The data drivers provide data to the pixel array a row at a time. The particular row is identified by a select scanner which sequentially selects each row of the pixel array to receive data from the data drivers.
In a preferred design, the LCDs include Sample/Hold (S/H) circuits. Generally, each S/H circuit includes a metal-oxide semiconductor (MOS) transistor serving as an analog switch for sampling a video signal and a holding capacitor for holding the sampled signal charge. The sampled data is subsequently provided to the pixel array via the data driver.
High resolution displays require wide bandwidth data channels. The bandwidth per channel can be reduced by increasing the number of input channels to a display. The minimum bandwidth for a given number of channels is achieved when the time allocated for providing data to each pixel in the pixel array equals the display refresh time divided by the number of pixels times the number of channels.
In a conventional LCD the display refresh time divided by the number of pixels is greater than the time allocated for providing data to each pixel. As a result, it is difficult to produce displays of higher resolution quality and a minimum channel bandwidth. Notwithstanding, there is a continuing need for a means for addressing a display organized into rows and columns such as a liquid crystal display.